The power supply
When the Type 80 sorter was introduced, standard AC power hadn’t fully taken over and parts of the United States used DC or 25 Hertz AC.[9] Thus, the sorter needed to handle fifteen different line inputs including unusual ones such as 115V DC or 230V 25 Hertz AC. Internally, the sorter circuits used 115V DC, a rather high voltage for “logic” circuits. If the line voltage was AC, the power supply used a transformer and selenium rectifiers (an early form of diode build from stacks of selenium disks) to produce DC. The Type 81 power supply was considerably more complicated since its vacuum tubes required -40V DC. To create this voltage, the power supply used a vacuum tube oscillator, another transformer and vacuum tube diodes.
Power supply for the IBM Type 83 card sorter. Filter capacitors are at top. The power transformer is on the left. Selenium rectifiers (left and right) are built from stacks of selenium disks.
By the time the Type 83 sorter was introduced, AC line power was almost universal, so a transformer could replace the oscillator power supply. The picture above shows the power supply in a Type 83 sorter, showing the large power transformer (left), capacitors (orange cylinders), and selenium rectifiers (gray finned objects at lower left and right). Needless to say, modern switching power supplies are much more compact and efficient than the early power supplies used in the sorters.
